The invention relates to a method and apparatus for reconstructing an image of an object and, in particular, an organ or body part.
An apparatus and method for mammography apparatus enables the breasts of patients to be examined using X-rays. The image is acquired using an image receiver comprising either a photographic plate or digital sensing means. When taking images, the patient's breast is held against the image receiver by means of a compression paddle. The compression paddle presses the breast against a receiver, compressing it in the direction of propagation of the X-rays. Examinations practiced using such apparatus comprise taking cranio-caudal and lateral views. Cranio-caudal views are taken by irradiating the breast from above so as to obtain a view thereof in an axis extending from the patient's head to her/his feet. A side view is taken by irradiating the patient from the side so as to obtain a view of the breast in an axis passing through the patient's body.
In conventional mammography, the compression paddle is movable not only in a direction parallel to the direction of the X-rays, but also in a direction perpendicular to the X-ray propagation direction (for example in the Senographe of GE Medical Systems). This makes it possible to freely position the compression paddle prior to fixing it in its breast compression position. Once the paddle is in the compression position, the compression paddle remains stationary.
The Planmed company is proposing a compression system in its Maxview apparatus that comprises a compression paddle and an image receiver associated with a film that is movable in a direction perpendicular to the X-ray propagation direction and perpendicular to the rib cage. This apparatus allows the breast to be alternately compressed and stretched, optionally several times, prior to taking the image and/or between different images. This apparatus can take images of the major portion of the breast.
In the apparatus described above, when taking images, the three-dimensional arrangement of the patient's breast tissue is projected onto an image plane. When examining a dense breast or one that includes numerous fibrous structures, tissue superimposition when taking images is a source of ambiguity in their interpretation.
Images of parts of the body can also be obtained by the technique of tomography. Tomography makes it possible to obtain an X-ray of a thin slice of an organ or body part at a desired depth. In this method, a body part is fixed between an image receiver and a compression paddle, and the radiation source can be moved around the body part. When examining a dense breast or one with numerous fibrous structures, tissue overlay when imaging leads to ambiguities in interpreting the views obtained.